The fight started this week with trial balloons in the media signaling that Obama plans to nominate Rice as secretary of state when Hillary Clinton steps down.

Sen. John McCain, R-Ariz., called Rice “not qualified,” and Sen. Lindsey Graham, R-S.C., said flatly, “I don’t trust her,” because of her statements about the Sept.?11 attack in Benghazi, Libya, that killed four Americans.

Obama, in an unusual show of emotion yesterday, defended Rice, the U.N. ambassador who has been a mainstay of his foreign-policy team since his 2008 campaign.

“If Sen. McCain and Sen. Graham want to go after somebody, they should go after me,” he said at a White House news conference. “To besmirch her reputation is outrageous.”

Rice has been under fire ever since she was dispatched by the Obama administration to tell Sunday talk shows five days after the Libya incident that it resulted from a spontaneous demonstration, a narrative that turned out to be false.

In defending Rice yesterday, Obama might have inadvertently suggested that she lacked the stature of a secretary of state, arguing that she was only a spokeswoman on the Libya story, reciting talking points given her by intelligence agencies.

Republicans weren’t buying that.

“This is about the role she played around four dead Americans when it seems to be that the story coming out of the administration — and she’s the point person — is so disconnected to reality, I don’t trust her,” Graham said. “The reason I don’t trust her is because I think she knew better, and if she didn’t know better, she shouldn’t be the voice of America.”

Unfair, protested Obama.

“But when they go after the U.N. ambassador, apparently because they think she’s an easy target, then they’ve got a problem with me,” Obama said. “If I think that she would be the best person to serve America in that capacity at the State Department, then I will nominate her.”

McCain said, “We will do whatever’s necessary to block the nomination that’s within our power as far as Susan Rice is concerned.”

Democrats were more sympathetic.

“She’s qualified to be secretary of state,” said Senate Armed Services Committee Chairman Carl Levin, D-Mich. “She may have had bad information.”